Vapenik, Jacqueline

In this study we compared the effects of the Toll-like receptor (TLR) ligands lipopolysaccharide (LPS), flagellin, the synthetic bacterial triacylated lipopeptide Pam3-Cys-Ser-Lys4 (Pam3CSK4), Polyinosinic:polycytidylic acid (Poly I:C), and macrophage-activating lipopeptide (MALP-2), which are TLR4, TLR5, TLR1/2, TLR3, and TLR2/6 agonists, respectively, on cell morphology and phagocytosis of zymosan particles, derived from Saccharomyces cerevisiae, and rich in fungal PAMPs including beta-glucan, mannose, and chitin. LPS, Pam3CSK4, and MALP-2 induced an activated macrophage phenotype and enhanced zymosan phagocytosis. In contrast, flagellin and Poly I:C, respectively, had little effect on cell morphology and phagocytosis. We examined the role of scavenger receptor A (SR-A) on zymosan phagocytosis. Cells cultured in medium alone expressed SR-A, and LPS induced further expression of the receptor. We also observed inhibitory effects of scavenger receptor antagonists fucoidan, dextran sulphate, and Polyinosinic (Poly I), respectively, on zymosan phagocytosis of cells in medium alone and those pre-treated with LPS. We conclude that exposure to specific TLR ligands impacts both cellular morphology and phagocytic capacity, and that scavenger receptors contribute to zymosan ingestion as well as LPS-induced augmentation of phagocytosis.--Publisher.

In recent years, information on the diversity and abundance of microorganisms associated with the human body has significantly expanded. Recent research on the microbiota reveals its importance in the maintenance of normal host physiology and particular dysbioses have been associated with disturbances of gastrointestinal and metabolic health, brain function, and immunological responses. College students in health sciences and related programs, to our knowledge, receive little information regarding the microbiota and its importance in health. Adequate descriptions of the microbiota are only recently starting to appear in undergraduate human anatomy and physiology textbooks and most curricula fail to address the topic of microbiota with the attention that it deserves. Given the growing amount of evidence demonstrating the vital role of the microbiota in body function, it is crucial to educate students about the microbiota in undergraduate human anatomy and physiology courses for health practitioners. In this review, we present examples of recent findings illustrating the importance of the microbiota, and discuss how we may incorporate the microbiota into the teaching of human anatomy and physiology courses

Background: Fungal and bacterial coinfections are common in surgical settings; however, little is known about the effects of polymicrobial interactions on the cellular mechanisms involved in innate immune recognition and phagocytosis. <p>Materials and methods: Zymosan particles, cell wall derivatives of the yeast Saccharomyces cerevisiae, are used to model fungal interactions with host immune cells since they display carbohydrates, including beta-glucan, that are characteristic of fungal pathogens. Using in vitro cell culture, RAW 264.7 macrophages were challenged with zymosan, and phagocytosis determined via light microscopy. The effects of different concentrations of lipopolysaccharide (LPS) on zymosan phagocytosis were assessed. In addition, the transfer of supernatant from LPS-treated cells to naive cells, the effects of soluble carbohydrates laminarin, mannan, or galactomannan, and the impact of complement receptor 3 (CR3) inhibition on phagocytosis were also determined. <p>Results: LPS enhanced phagocytosis of zymosan in a dose-dependent manner. Transfer of supernatants from LPS-primed cells to naı¨ve cells had no effect on phagocytosis. Laminarin inhibited zymosan phagocytosis in naı¨ve cells but not in LPS-primed cells. Neither mannan, galactomannan, nor CR3 inhibition had a significant effect on ingestion of unopsonized zymosan in naı¨ve or LPS-treated cells. <p>Conclusions: Zymosan recognition by naı¨ve cells is inhibited by laminarin, but not mannan, galactomannan, or CR3 inhibition. LPS enhancement of phagocytosis is laminarin insensitive and not mediated by supernatant factors or zymosan engagement by the mannose or CR3 receptors. Our data suggest alternative mechanisms of zymosan recognition in the presence and absence of LPS.